Griselbrand was relatively simple choice. We knew all along it was pretty busted. While we had a glimmer of hope that the batch-of-7 card draw would help mitigate the obvious problem of a player being able to draw so many cards immediately (like Yawgmoth’s Bargain, unlike Necropotence), it simply didn’t. Griselbrand’s Lifelink ability, allowing you more resources to draw cards with, coupled with being a creature and therefore easier to get into play (not to mention repeatedly) for far less than his mana cost, led to quite degenerate game states.

Sundering Titan has long been a card on the edge. The decision to get rid of it came from the combination of two points. One, it simply created undesirable game states. It was too easily both intentionally abused and unintentionally game-warping, especially since its ability triggers on both entering and leaving the battlefield. Two, there has been a fair amount of community distaste for the card, and we agreed that the card overwhelmingly creates a negative experience for players. Listening to the ever-growing and ever more-involved community is important to us.

There’s an M13 card—Worldfire—that’s been generating some talk. We’re going to keep a close eye on the card after its release to look at its impact and potential impact on the format, but there’s no reason to panic and pre-ban it. Banning cards is about what they do, not about what they might do, so like we did with Griselbrand, and despite what we see as a likely outcome, we’d like to see some evidence of it first.

As a side note, remember that there is ongoing Kokusho testing, so no decision will be made on it until the September update, at the earliest.